Prosthodontic restorations replacing a natural tooth in a patient's dentition are commonly fixed on a dental implant that is surgically implanted into the patient's jawbone. Typically, since the early work of Per-Ingvar Brånemark of Sweden in 1952, such an implant consists of a titanium screw which resembles a tooth root and comprises a roughened or smooth surface. The majority of dental implants are made out of pure titanium, which is commercially available in four grades depending upon the amount of contained carbon and iron.
An abutment is usually anchored at the coronal end of the dental implant. A dental prosthesis, such as a crown, a fixed bridge retainer or a removable denture, can be attached on the abutment serving as an interface between the dental prosthesis and the dental implant. The abutment is typically held in place with a screw. Abutments can be custom-made in a dental laboratory or purchased as a prefabricated part from a dental implant supplier.
Current implants are typically made of titanium, stainless steel or ceramics. The biocompatibility of these materials has been widely documented over the years, especially in the case of titanium and ceramics. Despite this benefit, all these materials have the disadvantage of being too stiff and brittle as compared to the dentine and cementum of a natural tooth they are supposed to replace and mimic. In consequence, the masticatory stresses exerted on the artificial tooth structure cannot be adequately absorbed. This leads to a number of undesirable side effects including an unnatural feeling of pressure while chewing, increased bruxism, and an increased risk of breakage of the artificial tooth structure. Another disadvantage lies in the different refractive index of these materials as compared to a natural tooth, resulting in an unnatural and unaesthetic appearance of the replacement structure. Moreover, these materials are difficult to rework, in particular to cut or grind or trim. In consequence, they are usually fabricated in specific standardized shapes which complicates an individual adaption to the shape of crown or bridge restorations.